* Play chess against the computer (any installed engine) from any position with flexible time controls
* Tournament or Fun mode with hints and drawbacks
* Automatic rating calculation
* Material handicaps and rating handicaps (ELO 700-2400) with rating based opening book
* Chess960/Fischerandom games
* Blindfold and semi-blindfold games

Openings books and trees

* State of the art chess trees (fast, powerful, compact)
* Advanced opening book creation and modification
* Fast and flexible move coloring system
* User defined move color priority (play only experimental moves where available etc.)
* Combine several trees into one tree configuration for unprecedented flexibility
* Use a discarded moves tree to mask certain moves or opening systems from being played
* Multiple, reusable discarded moves trees
* Add comments to trees – even visual annotations
* Build trees from a list of games

Databases

* A database with over 4 400 000 games
* Very fast searches.
* An opening book for chess engines
* A special rating handicap opening book for playing against the computer

* iBooks
* A powerful system for publishing chess texts in print and on the web
* Suitable for short texts (e.g. for a blog entry) as well as books containing hundreds of pages
* Images, diagrams (both full and partial), visual annotations
* Full flexibility in arranging order of pages, sections etc. until the document is published
* Printing and web publishing
* Print one or more games with annotations
* Publish games on the web with JavaScript replay option
* Blog export with support for Blogger.com

Chess Engines

* Chess engine support: Universal Chess Interface (UCI) protocol, WinBoard protocol
* There are hundreds of free and commercial chess engines are available and can be easily managed within Aquarium
* Install all engines from a selected directory with the click of a button
* Various engine tournaments and matches capabilities: